CA1172178A - Removal of sulfur from process streams - Google Patents
Removal of sulfur from process streamsInfo
- Publication number
- CA1172178A CA1172178A CA000390819A CA390819A CA1172178A CA 1172178 A CA1172178 A CA 1172178A CA 000390819 A CA000390819 A CA 000390819A CA 390819 A CA390819 A CA 390819A CA 1172178 A CA1172178 A CA 1172178A
- Authority
- CA
- Canada
- Prior art keywords
- sulfur
- zeolite
- zinc
- exchanged
- ion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/3408—Regenerating or reactivating of aluminosilicate molecular sieves
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
- C07C7/13—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers by molecular-sieve technique
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
- C10G25/02—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material
- C10G25/03—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material with crystalline alumino-silicates, e.g. molecular sieves
- C10G25/05—Removal of non-hydrocarbon compounds, e.g. sulfur compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S95/00—Gas separation: processes
- Y10S95/90—Solid sorbent
- Y10S95/902—Molecular sieve
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Water Supply & Treatment (AREA)
- Crystallography & Structural Chemistry (AREA)
- Separation Of Gases By Adsorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Treating Waste Gases (AREA)
- Industrial Gases (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process wherein a particulate sorbent mass of zeolite which has been ion-exchanged with zinc or cad-mium to provide pore size openings of about 5.ANG., and greater, particularly zinc, is contacted with a moist hydrocarbon process stream which contains sulfur, sulfur compounds, and other contaminants, these being adsorbed onto said particulate sorbent mass, and the process stream thereby denuded of said sulfur, sulfur compounds, and other contaminants. Thereafter, the sulfur, sulfur com-pounds, and other contaminants, are readily desorbed, or removed from said particulate sorbent mass by contacting, and purging same with a gas stream, suitably hydrogen, or a hydrogen-containing gas, at elevated temperature.
A process wherein a particulate sorbent mass of zeolite which has been ion-exchanged with zinc or cad-mium to provide pore size openings of about 5.ANG., and greater, particularly zinc, is contacted with a moist hydrocarbon process stream which contains sulfur, sulfur compounds, and other contaminants, these being adsorbed onto said particulate sorbent mass, and the process stream thereby denuded of said sulfur, sulfur compounds, and other contaminants. Thereafter, the sulfur, sulfur com-pounds, and other contaminants, are readily desorbed, or removed from said particulate sorbent mass by contacting, and purging same with a gas stream, suitably hydrogen, or a hydrogen-containing gas, at elevated temperature.
Description
1 Sulfur occurs in many industrial processes, and
2 sulfur, or sulfur containing compounds, for varying reasons
3 must often be removed from process streams, e.g , flue
4 gas, waste gas or recycle gas streams. This has been
5 accomplished, e.g., by contacting the sulfur-containing
6 process stream with a sorbent comprising a particulate
7 oxide, hydrated oxide, or hydroxide of alumina, zinc,
8 iron, nickel, cobalt or the like, alone or in admixture
9 with each other or with additional materials, e.g., alkali
10 or alkaline earth metal oxides or the like. Reference is
11 made, e.g., to U.S. 3,492,0~3 and British Patent 871,076
12 (1957) which describes processes of this type. Hot spheri-
13 cal pebbles have also been used to remove sulfur from
14 process streams, as described, e.g., in U.S. 2,551,905.
The ~uality of these sorbents for the removal 16 of sulfur varies considerably, and in many applications it 17 is necessary to scrub essentially all of the sulfur from 18 the process streams. This is done for process reasons, as 19 well as environmental reasons. Sulfur, for example, is a 20 well known catalyst poison which finds its way into a pro-21 cess principally via the feed, and it can gradually accumu-22 late upon and poison a catalyst. Essentially all petroleum 23 feeds contain sulfur. Most of the sulfur, because of this 24 adverse effect, is generally removed from the feed, e.g., 25 by contact with nickel or cobalt oxide guard chambers.
26 Catalytic reforming, or hydroforming, a well-27 known and important process employed in the petroleum 28 refining industry for improvinq the octane quality of 29 naphthas and straight run gasolines, is illustrative of a 30 process where the presence of sulfur can have a detrimental 31 effect. Sulfur unavoidably enters the process, principally 32 as a part of the feed. In a typical reforming process, a 33 series of reactors are provided with fixed beds of sulfided 34 platinum-containing catalysts which are sequentially con-35 tacted with a naphtha eed, and hydrogen, and each reactor 36 is provided with a preheater, or interstage heater, because 37 the reactions which take place are endothermic. Cs+
- 2 - 1 ~ 7 Z 1 7 8 1 hydrocarbons as a product is taken from the last reactor 2 of the series, and a hydrogen-sulfide contaminated hydrogen 3 gas stream is separated therefrom and recycled to the 4 several reactors of the series.
In use of the more recently developed multi-6 metallic platinum catalysts wherein an additional metal, or 7 metals hydrogenation-dehydrogenation component is added as 8 a promoter to the platinum, it has become essential to g reduce the feed sulfur to only a few parts, per million 10 parts by weight of feed (ppm), because of the sulfur sen-11 sitiveness of these catalysts. For example, in the use 12 of platinum-rhenium catalysts it is generally necessary to 13 reduce the sulfur concentration of the feed well below 14 about 10 ppm, and preferably well below about 2 ppm, to
The ~uality of these sorbents for the removal 16 of sulfur varies considerably, and in many applications it 17 is necessary to scrub essentially all of the sulfur from 18 the process streams. This is done for process reasons, as 19 well as environmental reasons. Sulfur, for example, is a 20 well known catalyst poison which finds its way into a pro-21 cess principally via the feed, and it can gradually accumu-22 late upon and poison a catalyst. Essentially all petroleum 23 feeds contain sulfur. Most of the sulfur, because of this 24 adverse effect, is generally removed from the feed, e.g., 25 by contact with nickel or cobalt oxide guard chambers.
26 Catalytic reforming, or hydroforming, a well-27 known and important process employed in the petroleum 28 refining industry for improvinq the octane quality of 29 naphthas and straight run gasolines, is illustrative of a 30 process where the presence of sulfur can have a detrimental 31 effect. Sulfur unavoidably enters the process, principally 32 as a part of the feed. In a typical reforming process, a 33 series of reactors are provided with fixed beds of sulfided 34 platinum-containing catalysts which are sequentially con-35 tacted with a naphtha eed, and hydrogen, and each reactor 36 is provided with a preheater, or interstage heater, because 37 the reactions which take place are endothermic. Cs+
- 2 - 1 ~ 7 Z 1 7 8 1 hydrocarbons as a product is taken from the last reactor 2 of the series, and a hydrogen-sulfide contaminated hydrogen 3 gas stream is separated therefrom and recycled to the 4 several reactors of the series.
In use of the more recently developed multi-6 metallic platinum catalysts wherein an additional metal, or 7 metals hydrogenation-dehydrogenation component is added as 8 a promoter to the platinum, it has become essential to g reduce the feed sulfur to only a few parts, per million 10 parts by weight of feed (ppm), because of the sulfur sen-11 sitiveness of these catalysts. For example, in the use 12 of platinum-rhenium catalysts it is generally necessary to 13 reduce the sulfur concentration of the feed well below 14 about 10 ppm, and preferably well below about 2 ppm, to
15 avoid excessive loss of catalyst activity and C5+ liquid
16 yield.
17 The sulfur must also be scrubbed from the
18 hydrogen recycle gas stream because this too is a source
19 of catalyst sulfur contamination. The vapor effluent from
20 the last reactor of the series is thus a gas rich in
21 hydrogen, which generally contain hydrogen chloride and
22 chlorine, as well as hydrogen sulfide, moisture and small
23 a unts of normally gaseous and C5-Cg hydrocarbons. It is
24 essential to separate hydrogen from the C5+ liquid product
25 and recycle it to the process; and it is essential to re-
26 move the sulfur from the moist recycle hydrogen gas stream.
27 This, as suggested, has been accomplished by the use of
28 guard chambers filled with metal oxides, e.g., zinc oxide,
29 supra.
Zinc oxide thus has been used as a sorbent 31 for selectively removing hydrogen sulfide from process 32 streams. Usually, the zinc oxide is contacted with the gas 33 at elevated temperatures to scrub out the sulfur. Such 34 sorbent, however, has not proven successful because the 35 adsorption rate is too low, and it has not been possible 36 to regenerate such sorbent in a reducing atmosphere such 37 as hydrogen due to the high thermodynamic stability of zinc - 3 _ ~7Z1~8 1 sulfide. Regeneration of this material requires oxida-2 tion of the sulfur, or sulfur-containing compounds, so 3 that the sulfur is evolved as sulfur oxides, an environ-4 mentally unacceptable product. Such regeneration impairs 5 the mechanical strength of the material. Moreover, sul-6 fur oxides are difficult to remove from flue gas effluents, 7 e.g., as contrasted with hydrogen sulfide which is easily 8 scrubbed from the stream with a caustic or amine solution.
9 Wolf and co-workers studied the adsorption of 10 hydrogen sulfide and methyl mercaptan on exchanged syn-11 thetic sodium -- A zeolites as a function of the degree 12 of cation exchange. F. Wolf, W. Hoese & H. Fuertig 13 (Martin-Luther Univ. Halle-Wittenberg; Chemiekombinat 14 Bitterfeld VEB) Chem. Tech. (Leipz.) 27 #6:362-64 (June 15 1975). For hydrogen sulfide, the capacities were found to 16 decrease in the order barium ~ potassium < strontium <
17 cobalt < nickel < zinc < manganese < sodium ~ magnesium <
18 calcium. For methyl mercaptan the capacities were found 19 comparable. The capacities of sodium X and sodium-potassium 20 X sieves for both sulfur compounds were slightly higher 21 than those of the corresponding A sieves. In earlier work 22 some members of the same group has found that zinc-A was 23 relatively poor in adsorbing mercaptans. F. Wolf & K. H.
24 Bergk (Univ. Hauc) Erdoel Xohle, Erdgas, Petrochem Brennst.
25 -Chem. 27 #10:623 (Oct. 1974); and this work was later con-26 firmed by Soviet researchers E. I. Shcherbina, V. A. Yaku-27 bovich & L. I. Mikhalrkaya (Beloruss. Technol. Inst., 28 Minsk) Neflekhimya 17 #1:151-55 (Jan. - Feb. 1977).
29 German Patent 2,226,531 which issued June 1973
Zinc oxide thus has been used as a sorbent 31 for selectively removing hydrogen sulfide from process 32 streams. Usually, the zinc oxide is contacted with the gas 33 at elevated temperatures to scrub out the sulfur. Such 34 sorbent, however, has not proven successful because the 35 adsorption rate is too low, and it has not been possible 36 to regenerate such sorbent in a reducing atmosphere such 37 as hydrogen due to the high thermodynamic stability of zinc - 3 _ ~7Z1~8 1 sulfide. Regeneration of this material requires oxida-2 tion of the sulfur, or sulfur-containing compounds, so 3 that the sulfur is evolved as sulfur oxides, an environ-4 mentally unacceptable product. Such regeneration impairs 5 the mechanical strength of the material. Moreover, sul-6 fur oxides are difficult to remove from flue gas effluents, 7 e.g., as contrasted with hydrogen sulfide which is easily 8 scrubbed from the stream with a caustic or amine solution.
9 Wolf and co-workers studied the adsorption of 10 hydrogen sulfide and methyl mercaptan on exchanged syn-11 thetic sodium -- A zeolites as a function of the degree 12 of cation exchange. F. Wolf, W. Hoese & H. Fuertig 13 (Martin-Luther Univ. Halle-Wittenberg; Chemiekombinat 14 Bitterfeld VEB) Chem. Tech. (Leipz.) 27 #6:362-64 (June 15 1975). For hydrogen sulfide, the capacities were found to 16 decrease in the order barium ~ potassium < strontium <
17 cobalt < nickel < zinc < manganese < sodium ~ magnesium <
18 calcium. For methyl mercaptan the capacities were found 19 comparable. The capacities of sodium X and sodium-potassium 20 X sieves for both sulfur compounds were slightly higher 21 than those of the corresponding A sieves. In earlier work 22 some members of the same group has found that zinc-A was 23 relatively poor in adsorbing mercaptans. F. Wolf & K. H.
24 Bergk (Univ. Hauc) Erdoel Xohle, Erdgas, Petrochem Brennst.
25 -Chem. 27 #10:623 (Oct. 1974); and this work was later con-26 firmed by Soviet researchers E. I. Shcherbina, V. A. Yaku-27 bovich & L. I. Mikhalrkaya (Beloruss. Technol. Inst., 28 Minsk) Neflekhimya 17 #1:151-55 (Jan. - Feb. 1977).
29 German Patent 2,226,531 which issued June 1973
30 to Gebr Herrmann discloses that Pb zeolites can be used
31 for hydrogen sulfide sorption, and that the lead can be
32 exchanged by other metals, inclusive of zinc. The Patentee,
33 however, states that such exchanged zeolites have not been
34 found of practical use.
Robert M. Miltonls U.S. Patents 3,078,640 and 36 3,024,868, which issued on applications filed in the last 37 weeks of the year 1959, are believed to exemplify the _ 4 _ ~ ~7~8 1 state-of-the-art as relates to the separation of sulfur-2 containing compounds from gaseous mixtures by the use of 3 molecular sieve adsorbents. In U.S. 3,078,640, which 4 issued February 26, 1963, certain forms of zeolite A are 5 suggested for use in the selective adsorption of hydrogen 6 sulfide from a vapor mixture containing at least one mem-7 ber of the group consisting of hydrogen, carbon dioxide 8 and normal saturated aliphatic hydrocarbons containing 9 less than nine carbon atoms per molecule. The reference 10 suggests that zeolite A can be used in its sodium form, 11 or the sodium ions of the zeolite can be substituted at 12 least in part by other metal ions from Group I and Group II
13 of the PeriodiclTable.The reference states that the various 14 ion exchanged forms of zeolite A includes the lithium, 15 ammonium, silver, zinc, nickel hydrogen and strontium 16 forms. It is 6tressed that the divalent metal substituted 17 forms of zeolite A, e.g., zinc, nickel and strontium zeo-18 lite A, behave quite differently from the monovalent metal19 substituted forms of zeolite A, e.g., lithium, and hydro-20 gen zeolite A. It suggests that any cationic form of 21 zeolite A having a pore size of at least 4 Angstroms is 22 suitable for practicing the invention; and conversely that23 smaller pore size forms are unsatisfactory because they do 24 not admit hydrogen sulfide and mercaptans. Albeit, how-25 ever, this reference describes the use of molecular sieves26 having pore sizes greater than 4A as a selective adsorbent 27 for the separation of suIfur-containing compounds from hydro-28 carbons, there is no suggestion of the separation, or ad-29 sorption, of sulfur containing compounds from moisture 30 bearing, or water containing streams. The separation of 31 sulfur compounds from moist, or wet streams presents a far32 more difficult problem inasmuch as water is preferentially 33 adsorbed to the exclusion of sulfur containing compounds, 34 and e.g., water generally replaces essentially all of the
Robert M. Miltonls U.S. Patents 3,078,640 and 36 3,024,868, which issued on applications filed in the last 37 weeks of the year 1959, are believed to exemplify the _ 4 _ ~ ~7~8 1 state-of-the-art as relates to the separation of sulfur-2 containing compounds from gaseous mixtures by the use of 3 molecular sieve adsorbents. In U.S. 3,078,640, which 4 issued February 26, 1963, certain forms of zeolite A are 5 suggested for use in the selective adsorption of hydrogen 6 sulfide from a vapor mixture containing at least one mem-7 ber of the group consisting of hydrogen, carbon dioxide 8 and normal saturated aliphatic hydrocarbons containing 9 less than nine carbon atoms per molecule. The reference 10 suggests that zeolite A can be used in its sodium form, 11 or the sodium ions of the zeolite can be substituted at 12 least in part by other metal ions from Group I and Group II
13 of the PeriodiclTable.The reference states that the various 14 ion exchanged forms of zeolite A includes the lithium, 15 ammonium, silver, zinc, nickel hydrogen and strontium 16 forms. It is 6tressed that the divalent metal substituted 17 forms of zeolite A, e.g., zinc, nickel and strontium zeo-18 lite A, behave quite differently from the monovalent metal19 substituted forms of zeolite A, e.g., lithium, and hydro-20 gen zeolite A. It suggests that any cationic form of 21 zeolite A having a pore size of at least 4 Angstroms is 22 suitable for practicing the invention; and conversely that23 smaller pore size forms are unsatisfactory because they do 24 not admit hydrogen sulfide and mercaptans. Albeit, how-25 ever, this reference describes the use of molecular sieves26 having pore sizes greater than 4A as a selective adsorbent 27 for the separation of suIfur-containing compounds from hydro-28 carbons, there is no suggestion of the separation, or ad-29 sorption, of sulfur containing compounds from moisture 30 bearing, or water containing streams. The separation of 31 sulfur compounds from moist, or wet streams presents a far32 more difficult problem inasmuch as water is preferentially 33 adsorbed to the exclusion of sulfur containing compounds, 34 and e.g., water generally replaces essentially all of the
35 hydroger. sulfide from an adsorbent contacted with a stream
36 containing both water and hydrogen sulfide.
37 On the other hand, in U.S. 3,024,868, which 1~ 7~3 1 issued March 13, 1962, there is specifically described a 2 process useful for the separation of sulfur containing 3 compounds from moist vaporous streams. In particular, the 4 process described is one useful for removing moisture and 5 sulfur containing compounds, notably hydrogen sulfide, from 6 the recycle hydrogen gas stream of a reformer by contact 7 of the stream with crystalline zeolitic molecular sieves 8 having pore sizes ranging from about 3.6 to 4A. Both the 9 water and sulfur containing compounds are sorbed preferen-10 tially, to the exclusion of the saturated paraffinic 11 hydrocarbons. It is expressly stated that molecular sieves 12 having larger pore sizes, viz. >4A, strongly preferentially 13 adsorb and concentrate the C4 and higher paraffins. Any 14 substitution o~ the sodium zeolite A with monovalent or 15 divalent metal ions which enlarges the pore size beyond 16 this limit ls thus, according to Milton, to be avoided.
17 This adverse effect, according to Milton, is particularly 18 apparent with divalent cation forms of zeolite, the en-19 largement being manifested above about 25 percent substi-20 tution of divalent ions in the molecular sieve structure.
21 Data presented in the patent show that zeolite 4A has 22 eight to ten times the adsorptive capacity for water and 23 hydrogen sulfide as zeolite 5A and zeolite 13X, with con-24 current high exclusion or rejection of the hydrocarbons.
In Milton's process a reformer recycle hydrogen 26 gas stream is desulfided by contact with at least two 27 separate beds of the zeolite 4Aj the wet reformer hydrogen 28 gas stream being contacted with a first bed in an adsorp-29 tion stroke at relatively low temperature and pressure, 30 while water and sulfur containing compounds are desorbed 31 from a second bed in a desorption stroke at relatively 32 high temperature and pressure. The flows between the beds 33 are periodically reversed such that the first bed i5 on an 34 adsorption stroke while the second bed is on a desorption 35 stroke, and vice-versa.
36 ~ereas commercial processes based on the use of 37 metal oxides for adsorption of sulfur from process streams - 6 - ~ ~7~
1 have provided varying degrees of success, there is 2 little evidence that the zeolites have attracted any 3 significant commercial interest, if any, for this use.
4 A considerable need therefore exists for the development 5 of new and improved processes of this type, especially 6 those which are capable of adsorbing, and separating 7 sulfur containing compounds from moist hydrocarbon streams;
8 notably hydrogen sulfide-containing reforming hydrogen g recycle gas.
It is an object of this present invention to 11 provide a new and improved process, particularly one uti-12 lizing a sorbent which is capable of high rates of sulfur 13 adsorption from process streams, and more particularly one 14 which can be regenerated without significant loss of 15 mechanical strength, if any.
16 This object is achieved in accordance with the 17 present invention, embodying a process wherein a particulate 18 sorbent mass of zeolite which has been ion-exchanged with 19 zinc or cadmium, particularly zinc, sufficient to provide O O
20 pore size openings greater than 4A, preferably 5A and 21 greater, most preferably from about 5A to about 13A, is 22 contacted with a moisture bearing, hydrocarbon process 23 stream which contains sulfur, sulfur compounds, and other 24 contaminants, these are adsorbed onto said particulate 25 mass of ion-exchanged zeolite, and the process stream 26 thereby denuded of said sulfur, sulfur compounds, and other 27 contaminants. Thereafter, the sulfur, sulfur compounds, 28 and other contaminants, are readily desorbed, or removed 29 from said particulate mass of ion-exchanged zeolite by 30 contacting, and purging same with a gas stream, suitably 31 hydrogen, hydrogen-containing gas, or inert gas such as 32 nitrogen or methane at elevated temperature.
33 Various zeolites ion-exchanged with zinc or 34 cadmium metals are useful in accordance with this inven-35 tion inclusive of intermediate and large pore zeolites.
36 Preferred ion-exchanged zeolites include mordenite, 37 faujasite, erionite, ferrierite, zeolite A, ZSM-5, zeolite X
1~7~7~
1 and Y, chabazite, both natural and synthetic having 2 pore size openings greater than 4A, preferably 5A and 3 greater; especially those having pore size openings 4 ranging from about 5A to about 13A. The A type zeolite 5 is preferred, especially one which is ion-exchanged with 6 a zinc salt, sufficient to provide pore size openings of 7 about 5A, and greater. Exchange of at least about 25 per-8 cent, and certainly 65 percent of the sodium ions of an 9 A type zeolite with zinc, or cadmium, is found to produce 10 zeolite 5A. In fact, it is found that the adsorption 11 behavior of most of the zeolites, especially zeolite A, 12 begins to change when greater than about 25 percent of 13 the sodium ions are exchanged with the multivalent cation, 14 zinc or cadmium, the pore size openings increasing their 15 normal sizes, especially zeolite A which increases beyond 16 4A. Such divalent forms of zeolite A are found far more 17 effective for the selective adsorption of sulfur containing 18 compounds~than the small pore species o~ zeolite A pre-l9 viously known for such use, supra.
In a preferred operation, a particulate mass of 21 ion-exchanged zeolite, notably zinc exchanged zeolite, is 22 chargedj or packed into a guard chamber, or series of guard 23 chambers. Most preferably, the series of zinc exchanged 24 zeolite guard chambers are employed in parallel, this per-25 mitting active use of one guard chamber, or set of serially 26 aligned guard chambers for contact, and purification of a 27 process stream while the other guard~chamber, or set of 28 serially aligned guard chambers, is cut out of series for 29 regeneration. In the treatment of a hydrogen recycle gas 30 stream, as employed in reforming, it is found that the 31 hydrogen sulfide can be readily adsorbed from the stream 32 despite the high moisture content of the gas. This is 33 mildly surprising because it is well known that the selec-34 tivity of many sorbents for hydrogen sulfide is adversely 35 affected in the presence of water~ As a class, the zeolites, 36 in particular, show a preferential adsorption of water, this 37 Fesulting in a low capacity of the zeolites for the selectlve - 8 - ~17Z~7~
1 removal of hydrogen sulfide. The zinc, and cadmium-2 exchange zeolite, notably the zinc exchanged zeolite, 3 shows a high capacity for adsorption of the hydrogen 4 sulfide, several times that of many sulfur sorbent materials.
5 No special preparation of the particulate ion-exchanged zeo-6 lite of this invention is required, and it can be employed 7 in a guard chamber as powder, spheres, tablets, pellets 8 extrudates, irregular shaped particles, or the like in 9 virtually any size.
The temperature of contact is not critical, 11 and there is no necessity to heat or cool the process 12 stream, notably the recycle gas stream. Suitably, the 13 recycle hydrogen stream is contacted with the particulate 14 zinc exchanged zeolite sorbent at normal gas stream tempera-15 tures, i.e., at temperatures ranging from about ambient to 16 about 500F, or more generally at temperatures ranging 17 from about 100F to about 300F.
18 It would appear, surprisingly, that the metal 19 atoms of the zeolite structure, notably the zinc atoms of 20 the zinc exchanged zeolite, forms simple adsorption bonds 21 with the sulfur compound, this being sufficient to remove, 22 e.g., hydrogen sulfide from a recycle hydrogen gas stream.
23 Unlike the mechanism involved in the removal of a sulfur 24 compound,~e.g., hydrogen sulfide, from a recycle hydrogen 25 gas stream by the use of zinc oxide, there is no chemical 26 reaction wherein zinc sulfide is formed. Apparently, as 27 a consequence thereof the zinc exchanged zeolite is readily 28 regenerated by simply purging, or sweeping the sulfur com-29 pound therefrom with a hot, non-reactive, or inert gas 30 after it has become sufficiently saturated with the sulfur 31 compound. In the preferred practice of this invention, the 32 zinc exchanged zeolite is simply contacted, purged, or 33 swept with a hyarogen gas stream at elevated temperature to 34 remove the hydrogen sulfide, and other sulfur compounds, and 35 thereby regenerate the zinc exchanged zeolite. Suitably, 36 the purge is conducted by maintaining the hydrogen gas at 37 temperatures ranging from about 300F to about 1200F, .~ ' .
9 ~7Z~7~
1 preferably from about 500F to about 1000F. Since 2 burning in the presence of oxygen as practiced in the 3 regeneration of many sorbents is unnecessary, the 4 hydrogen sulfide is recovered as hydrogen sulfide rather 5 than as sulfur oxides. Consequently, the hydrogen gas 6 stream itself is readily cleansed of the hydrogen sulfide 7 by washing the gas with a caustic or amine solution.
8 The invention will be more fully understood 9 by reference to the following examples, and comparative 10 data which demonstrate the high selectivities for hydrogen 11 sulfide of the zeolites of this invention in the presence 12 of water. All terms are given in weight units except as 13 otherwise specified.
14 RX~PLES
A series of different commercially known zeolites, 16 as identified hereafter, were exchanged with an aqueous 17 solution of zinc chloride,~ZnC12. This was followed by 18 filtration and washing until the filtrate was free of 19 chloride as determined by testlng with an AgNO3 solution.
20 The zeolites were then vacuum dried, and calcined in air 21 for three hours at 800F. To measure H2S adsorption, the 22 zeolite was packed into a quartz reactor maintained at 23 200F and a stream of 2000 ppm. H2S in H2 at atmospheric 24 pressure passed through until breakthrough occurred. This 25 was observed by the discoloration of lead acetate paper.
26 For regeneration, the adsorbents were heated either to 27 500F or to 932F while stripping with H2 gas. The adsorp-28 of H2S was then redetermined at a standardized temperature 29 of 200F. Data on several ~Zn exchanged~zeolites are shown 30 in the Table and/or compared with the unexchanged or 31 corresponding natural zeolite.
::
- lo ~ 7~
1 Table 2 Exchan~ed Zeolites 3 Wt. % S Adsorbed @ 200F, 1 Atm.
4 From A 2000 ppm H2S in H2 Stream Cycle 2 Cycle 3 6 After After 8 Wt. ~ ~ Na Cycle 1 Strip Str1p g AdsorbentZn Exchanged Original @ 932F @ 50~F
10 Na Zeolite A
11 (4A Sieve) 0 0 0.22 12 Zn Zeolite A
13 (Zn 5A) 14.5 65 2.37 3.02 2.0 14 Cd Zeolite A - 50 2.38 1.27 15 Ni Zeolite Aa 16 0.76 0.58 16 Co Zeolite A - 42 0.85 1.40 17 Cu Zeolite Aa,b _ 77 0 47 0 18 Hg Zeolite Aa~b _ 100 0.40 - -19 Zn Exchanged 20 Erionite 5.79 1.12 27 Natural 22 Chabazite o o ~ 0.96 ~-23 Zn Chabazite 6.33 -~ ~ 1.51 1.87 24 Na Mordenite 0 0 ~ 1.08 25 Zn Mordenite 3.67 ~ 1.25 Z~ 26 aPartial destruction of~the zeolite A crystal structure \
2~7 occurred during the ion-exchange.~
28;~bAssuming~+2 valence state~for;Cu~and~Hg.
29 ~ From these data, it will be~initially observed 30 that the original sodium zeolite A (4A sieve) had very 31~limited~oapacity for H25 under~these~condltlons. The Zn 32 5A form,~however~, had a~capacity~nearly ten times as great.
` 33~Furthermore, a~simple hydrogen strip was efective~for 34 re~géneration of the sorbent.~ The~increase~in capacity in ; 35 going from 2.37 wt. ~ in~Cycle~1~to 3.02 wt. ~ in Cycle 2 36 is attributable to the higher g32F regeneration t~mpera-37 ture compared to the 800F original air calcinaticn. The
17 This adverse effect, according to Milton, is particularly 18 apparent with divalent cation forms of zeolite, the en-19 largement being manifested above about 25 percent substi-20 tution of divalent ions in the molecular sieve structure.
21 Data presented in the patent show that zeolite 4A has 22 eight to ten times the adsorptive capacity for water and 23 hydrogen sulfide as zeolite 5A and zeolite 13X, with con-24 current high exclusion or rejection of the hydrocarbons.
In Milton's process a reformer recycle hydrogen 26 gas stream is desulfided by contact with at least two 27 separate beds of the zeolite 4Aj the wet reformer hydrogen 28 gas stream being contacted with a first bed in an adsorp-29 tion stroke at relatively low temperature and pressure, 30 while water and sulfur containing compounds are desorbed 31 from a second bed in a desorption stroke at relatively 32 high temperature and pressure. The flows between the beds 33 are periodically reversed such that the first bed i5 on an 34 adsorption stroke while the second bed is on a desorption 35 stroke, and vice-versa.
36 ~ereas commercial processes based on the use of 37 metal oxides for adsorption of sulfur from process streams - 6 - ~ ~7~
1 have provided varying degrees of success, there is 2 little evidence that the zeolites have attracted any 3 significant commercial interest, if any, for this use.
4 A considerable need therefore exists for the development 5 of new and improved processes of this type, especially 6 those which are capable of adsorbing, and separating 7 sulfur containing compounds from moist hydrocarbon streams;
8 notably hydrogen sulfide-containing reforming hydrogen g recycle gas.
It is an object of this present invention to 11 provide a new and improved process, particularly one uti-12 lizing a sorbent which is capable of high rates of sulfur 13 adsorption from process streams, and more particularly one 14 which can be regenerated without significant loss of 15 mechanical strength, if any.
16 This object is achieved in accordance with the 17 present invention, embodying a process wherein a particulate 18 sorbent mass of zeolite which has been ion-exchanged with 19 zinc or cadmium, particularly zinc, sufficient to provide O O
20 pore size openings greater than 4A, preferably 5A and 21 greater, most preferably from about 5A to about 13A, is 22 contacted with a moisture bearing, hydrocarbon process 23 stream which contains sulfur, sulfur compounds, and other 24 contaminants, these are adsorbed onto said particulate 25 mass of ion-exchanged zeolite, and the process stream 26 thereby denuded of said sulfur, sulfur compounds, and other 27 contaminants. Thereafter, the sulfur, sulfur compounds, 28 and other contaminants, are readily desorbed, or removed 29 from said particulate mass of ion-exchanged zeolite by 30 contacting, and purging same with a gas stream, suitably 31 hydrogen, hydrogen-containing gas, or inert gas such as 32 nitrogen or methane at elevated temperature.
33 Various zeolites ion-exchanged with zinc or 34 cadmium metals are useful in accordance with this inven-35 tion inclusive of intermediate and large pore zeolites.
36 Preferred ion-exchanged zeolites include mordenite, 37 faujasite, erionite, ferrierite, zeolite A, ZSM-5, zeolite X
1~7~7~
1 and Y, chabazite, both natural and synthetic having 2 pore size openings greater than 4A, preferably 5A and 3 greater; especially those having pore size openings 4 ranging from about 5A to about 13A. The A type zeolite 5 is preferred, especially one which is ion-exchanged with 6 a zinc salt, sufficient to provide pore size openings of 7 about 5A, and greater. Exchange of at least about 25 per-8 cent, and certainly 65 percent of the sodium ions of an 9 A type zeolite with zinc, or cadmium, is found to produce 10 zeolite 5A. In fact, it is found that the adsorption 11 behavior of most of the zeolites, especially zeolite A, 12 begins to change when greater than about 25 percent of 13 the sodium ions are exchanged with the multivalent cation, 14 zinc or cadmium, the pore size openings increasing their 15 normal sizes, especially zeolite A which increases beyond 16 4A. Such divalent forms of zeolite A are found far more 17 effective for the selective adsorption of sulfur containing 18 compounds~than the small pore species o~ zeolite A pre-l9 viously known for such use, supra.
In a preferred operation, a particulate mass of 21 ion-exchanged zeolite, notably zinc exchanged zeolite, is 22 chargedj or packed into a guard chamber, or series of guard 23 chambers. Most preferably, the series of zinc exchanged 24 zeolite guard chambers are employed in parallel, this per-25 mitting active use of one guard chamber, or set of serially 26 aligned guard chambers for contact, and purification of a 27 process stream while the other guard~chamber, or set of 28 serially aligned guard chambers, is cut out of series for 29 regeneration. In the treatment of a hydrogen recycle gas 30 stream, as employed in reforming, it is found that the 31 hydrogen sulfide can be readily adsorbed from the stream 32 despite the high moisture content of the gas. This is 33 mildly surprising because it is well known that the selec-34 tivity of many sorbents for hydrogen sulfide is adversely 35 affected in the presence of water~ As a class, the zeolites, 36 in particular, show a preferential adsorption of water, this 37 Fesulting in a low capacity of the zeolites for the selectlve - 8 - ~17Z~7~
1 removal of hydrogen sulfide. The zinc, and cadmium-2 exchange zeolite, notably the zinc exchanged zeolite, 3 shows a high capacity for adsorption of the hydrogen 4 sulfide, several times that of many sulfur sorbent materials.
5 No special preparation of the particulate ion-exchanged zeo-6 lite of this invention is required, and it can be employed 7 in a guard chamber as powder, spheres, tablets, pellets 8 extrudates, irregular shaped particles, or the like in 9 virtually any size.
The temperature of contact is not critical, 11 and there is no necessity to heat or cool the process 12 stream, notably the recycle gas stream. Suitably, the 13 recycle hydrogen stream is contacted with the particulate 14 zinc exchanged zeolite sorbent at normal gas stream tempera-15 tures, i.e., at temperatures ranging from about ambient to 16 about 500F, or more generally at temperatures ranging 17 from about 100F to about 300F.
18 It would appear, surprisingly, that the metal 19 atoms of the zeolite structure, notably the zinc atoms of 20 the zinc exchanged zeolite, forms simple adsorption bonds 21 with the sulfur compound, this being sufficient to remove, 22 e.g., hydrogen sulfide from a recycle hydrogen gas stream.
23 Unlike the mechanism involved in the removal of a sulfur 24 compound,~e.g., hydrogen sulfide, from a recycle hydrogen 25 gas stream by the use of zinc oxide, there is no chemical 26 reaction wherein zinc sulfide is formed. Apparently, as 27 a consequence thereof the zinc exchanged zeolite is readily 28 regenerated by simply purging, or sweeping the sulfur com-29 pound therefrom with a hot, non-reactive, or inert gas 30 after it has become sufficiently saturated with the sulfur 31 compound. In the preferred practice of this invention, the 32 zinc exchanged zeolite is simply contacted, purged, or 33 swept with a hyarogen gas stream at elevated temperature to 34 remove the hydrogen sulfide, and other sulfur compounds, and 35 thereby regenerate the zinc exchanged zeolite. Suitably, 36 the purge is conducted by maintaining the hydrogen gas at 37 temperatures ranging from about 300F to about 1200F, .~ ' .
9 ~7Z~7~
1 preferably from about 500F to about 1000F. Since 2 burning in the presence of oxygen as practiced in the 3 regeneration of many sorbents is unnecessary, the 4 hydrogen sulfide is recovered as hydrogen sulfide rather 5 than as sulfur oxides. Consequently, the hydrogen gas 6 stream itself is readily cleansed of the hydrogen sulfide 7 by washing the gas with a caustic or amine solution.
8 The invention will be more fully understood 9 by reference to the following examples, and comparative 10 data which demonstrate the high selectivities for hydrogen 11 sulfide of the zeolites of this invention in the presence 12 of water. All terms are given in weight units except as 13 otherwise specified.
14 RX~PLES
A series of different commercially known zeolites, 16 as identified hereafter, were exchanged with an aqueous 17 solution of zinc chloride,~ZnC12. This was followed by 18 filtration and washing until the filtrate was free of 19 chloride as determined by testlng with an AgNO3 solution.
20 The zeolites were then vacuum dried, and calcined in air 21 for three hours at 800F. To measure H2S adsorption, the 22 zeolite was packed into a quartz reactor maintained at 23 200F and a stream of 2000 ppm. H2S in H2 at atmospheric 24 pressure passed through until breakthrough occurred. This 25 was observed by the discoloration of lead acetate paper.
26 For regeneration, the adsorbents were heated either to 27 500F or to 932F while stripping with H2 gas. The adsorp-28 of H2S was then redetermined at a standardized temperature 29 of 200F. Data on several ~Zn exchanged~zeolites are shown 30 in the Table and/or compared with the unexchanged or 31 corresponding natural zeolite.
::
- lo ~ 7~
1 Table 2 Exchan~ed Zeolites 3 Wt. % S Adsorbed @ 200F, 1 Atm.
4 From A 2000 ppm H2S in H2 Stream Cycle 2 Cycle 3 6 After After 8 Wt. ~ ~ Na Cycle 1 Strip Str1p g AdsorbentZn Exchanged Original @ 932F @ 50~F
10 Na Zeolite A
11 (4A Sieve) 0 0 0.22 12 Zn Zeolite A
13 (Zn 5A) 14.5 65 2.37 3.02 2.0 14 Cd Zeolite A - 50 2.38 1.27 15 Ni Zeolite Aa 16 0.76 0.58 16 Co Zeolite A - 42 0.85 1.40 17 Cu Zeolite Aa,b _ 77 0 47 0 18 Hg Zeolite Aa~b _ 100 0.40 - -19 Zn Exchanged 20 Erionite 5.79 1.12 27 Natural 22 Chabazite o o ~ 0.96 ~-23 Zn Chabazite 6.33 -~ ~ 1.51 1.87 24 Na Mordenite 0 0 ~ 1.08 25 Zn Mordenite 3.67 ~ 1.25 Z~ 26 aPartial destruction of~the zeolite A crystal structure \
2~7 occurred during the ion-exchange.~
28;~bAssuming~+2 valence state~for;Cu~and~Hg.
29 ~ From these data, it will be~initially observed 30 that the original sodium zeolite A (4A sieve) had very 31~limited~oapacity for H25 under~these~condltlons. The Zn 32 5A form,~however~, had a~capacity~nearly ten times as great.
` 33~Furthermore, a~simple hydrogen strip was efective~for 34 re~géneration of the sorbent.~ The~increase~in capacity in ; 35 going from 2.37 wt. ~ in~Cycle~1~to 3.02 wt. ~ in Cycle 2 36 is attributable to the higher g32F regeneration t~mpera-37 ture compared to the 800F original air calcinaticn. The
38 regeneration a~ 500F is effective in~restoring capacity
39 in Cycle 3 to nearly that observed in Cycle 1.
Thé sodium form~of zeoIite A has the formula ~ Na12[(A12)12(5i2)12]-XH2~ thls material being designed :,`: ~ ' ~ :
, ~
~1~72~
1 4A because 4A approximates the effective pore size 2 openings of this material in Angstroms. Zeolite 4A
3 will not adsorb propane. When zeolite A is ion-exchanged 4 with potassium so that its chemical composition becomes 5 K12 [ (AlO2) 12 (SiO2) 12] XH2O, its effective diameter becomes 6 3R and hence is known as 3A. It adsorbes H20, NH3, and 7 methanol but not ethane.
8 If zeolite A is exchanged with sufficient of a 9 multivalent cation, e.g., Ca, the effective pore diameter 10 can become 5A, and such material is designated as 5A.
11 This material will adsorb n-paraffins such as n-heptane.
12 It is well known, e.g., by reference to the literature that 13 at least 25% of the Na ions have to be exchanged with cal-14 cium to enable its pore diameter to increase in size (See, 15 e.g., U.S. 3,024,968, col. 3, lines 36-44). Profound 16 changes in adsorption behavior also occur when greater than 17 25% of the sodium ions are exchanged with a multivalent 18 cation, e.g., Ca. In accordance with the present invention 19 the various forms of zeolite are ion-exchanged with zinc 20 or cadmium, preferably zinc; and where the pore openings ~-21 of the zeolite are of lesser effective diameter than 5A
22 the zeolite is nonetheless suitable if the diameters of 23 the pore size opening can be increased by exchange to pro- -24 vide pore openings of about 5A, and greater. Of course, 25 zeolite with pore size diameters initially greater than 26 5A effective pore size diameter need only be ion-exchanged 27 with zinc or cadmium, preferably zinc, to render them 28 suitable for use in accordance with the present invention.
29 With continued reference to the Table, it will 30 be observed that zinc exchange with chabazite improves its 31 capacity, and the material can also be regenerated by 32 hydrogen. Although the capacity is generally less than 33 that o Zn4A, chabazite is structurally more stable in acid 34 environments. The other acid resistant zeolites, mordenite 35 and erionite, also show improved capacity for H2S adsorp-36 tion upon Zn exchange.
37 A feature of this invention lies in the improved ~17~171~ ~-l selectivity of the ion-exchanged zeolites of this 2 invention for H2S removal from reformer recycle gas.
3 This permits the realization or higher activity, yields 4 and stability for reforming catalysts, notably bimetallic 5 catalysts. Unlike ZnO, the Zn zeolites also serve to 6 remove water and to be easily regenerable with hydrogen 7 strlpping.
8 It is apparent that various modifications and g changes can be made without departing from the spirit 10 and scope of the invention.
11 For example, the ion-exchanged molecular sieves 12 of this invention can be used in combination with metal 13 alumina spinels, by charging each type of adsorbent to 14 guard chambers and using the guard chambers in series. The 15 ion-exchanged molecular sieves show good sulfur adsorption 16 properties, and superior water adsorption properties. The 17 metal alumina spinels show superior sulfur adsorption pro- -18 pertles.
: ~ :
-:
Thé sodium form~of zeoIite A has the formula ~ Na12[(A12)12(5i2)12]-XH2~ thls material being designed :,`: ~ ' ~ :
, ~
~1~72~
1 4A because 4A approximates the effective pore size 2 openings of this material in Angstroms. Zeolite 4A
3 will not adsorb propane. When zeolite A is ion-exchanged 4 with potassium so that its chemical composition becomes 5 K12 [ (AlO2) 12 (SiO2) 12] XH2O, its effective diameter becomes 6 3R and hence is known as 3A. It adsorbes H20, NH3, and 7 methanol but not ethane.
8 If zeolite A is exchanged with sufficient of a 9 multivalent cation, e.g., Ca, the effective pore diameter 10 can become 5A, and such material is designated as 5A.
11 This material will adsorb n-paraffins such as n-heptane.
12 It is well known, e.g., by reference to the literature that 13 at least 25% of the Na ions have to be exchanged with cal-14 cium to enable its pore diameter to increase in size (See, 15 e.g., U.S. 3,024,968, col. 3, lines 36-44). Profound 16 changes in adsorption behavior also occur when greater than 17 25% of the sodium ions are exchanged with a multivalent 18 cation, e.g., Ca. In accordance with the present invention 19 the various forms of zeolite are ion-exchanged with zinc 20 or cadmium, preferably zinc; and where the pore openings ~-21 of the zeolite are of lesser effective diameter than 5A
22 the zeolite is nonetheless suitable if the diameters of 23 the pore size opening can be increased by exchange to pro- -24 vide pore openings of about 5A, and greater. Of course, 25 zeolite with pore size diameters initially greater than 26 5A effective pore size diameter need only be ion-exchanged 27 with zinc or cadmium, preferably zinc, to render them 28 suitable for use in accordance with the present invention.
29 With continued reference to the Table, it will 30 be observed that zinc exchange with chabazite improves its 31 capacity, and the material can also be regenerated by 32 hydrogen. Although the capacity is generally less than 33 that o Zn4A, chabazite is structurally more stable in acid 34 environments. The other acid resistant zeolites, mordenite 35 and erionite, also show improved capacity for H2S adsorp-36 tion upon Zn exchange.
37 A feature of this invention lies in the improved ~17~171~ ~-l selectivity of the ion-exchanged zeolites of this 2 invention for H2S removal from reformer recycle gas.
3 This permits the realization or higher activity, yields 4 and stability for reforming catalysts, notably bimetallic 5 catalysts. Unlike ZnO, the Zn zeolites also serve to 6 remove water and to be easily regenerable with hydrogen 7 strlpping.
8 It is apparent that various modifications and g changes can be made without departing from the spirit 10 and scope of the invention.
11 For example, the ion-exchanged molecular sieves 12 of this invention can be used in combination with metal 13 alumina spinels, by charging each type of adsorbent to 14 guard chambers and using the guard chambers in series. The 15 ion-exchanged molecular sieves show good sulfur adsorption 16 properties, and superior water adsorption properties. The 17 metal alumina spinels show superior sulfur adsorption pro- -18 pertles.
: ~ :
-:
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the removal of sulfur from a moisture-bearing, sulfur containing hydrocarbon process stream which comprises contacting said stream with a particulate mass of zeolite sufficiently ion-exchanged with zinc or cadmium to provide pore size openings of about 5.ANG., and greater, to adsorb sulfur thereon, and after completion of the sulfur sorption cycle, contacting said ion exchanged zeolite with an essentially non-reactive gas or reducing gas at elevated temperature, the sulfur being desorbed and the sorbent thereby regenerated.
2. The process of Claim 1 wherein the ion-exchanged zeolite is sodium zeolite A ion-exchanged with zinc sufficient to replace at least about 25 percent of the sodium of the original zeolite A.
3. The process of Claim 1 wherein the ion-exchanged zeolite is zinc exchanged zeolite A or zinc exchanged chabazite.
4. The process of Claim 1 wherein the gas em-ployed to desorb the sulfur from the ion-exchanged zeolite is comprised of hydrogen.
5. The process of Claim 1 wherein the ion-exchanged zeolite is a zinc exchanged zeolite, and the zinc exchanged zeolite sorbent is contacted with an essentially hydrogen gas at elevated temperature to desorb the sulfur and regenerate the sorbent.
6. The process of Claim 5 wherein the hydrogen is contacted with said zinc exchanged zeolite sorbent at temperatures ranging from about 400°F to about 1200°F.
7. The process of Claim 6 wherein the hydrogen is contacted with said zinc exchanged zeolite sorbent at temperatures ranging from about 800°F to about 1000°F.
8. In a process for the removal of sulfur from a moisture-bearing, sulfur containing process stream where-in a series of on-stream reactors are provided with beds of a sulfur sensitive platinum-containing catalyst, a naphtha feed with hydrogen is cocurrently passed sequen-tially through said series of reactors, and a vaporous effluent rich in hydrogen is taken from the last reactor of the series, hydrogen is separated from the products and recycled, the improvement which comprises contacting said stream with a particulate mass of zeolite sufficiently ion-exchanged with zinc or cadmium to provide pore size openings of about 5.ANG., and greater, to adsorb sulfur thereon, and after completion of the sul-fur sorption cycle, contacting said ion-exchanged zeolite with an essentially non-reactive gas or reducing gas at elevated temperature, the sulfur being desorbed and the sorbent thereby regenerated.
9. The process of Claim 8 wherein the ion-exchanged zeolite is sodium zeolite A ion-exchanged with zinc sufficient to replace at least about 25 percent of the sodium of the original zeolite A.
10. The process of Claim 8 wherein the ion-exchanged zeolite is a zinc exchanged zeolite A or zinc exchanged chabazite.
11. The process of Claim 9 wherein the ion-exchanged zeolite is a zinc exchanged zeolite, and the zinc exchanged zeolite sorbent is contacted with an essentially hydrogen gas at elevated temperature to desorb the sulfur and regenerate the sorbent.
12. The process of Claim 11 wherein the hydrogen is contacted with said zinc exchanged zeolite sorbent at temperatures ranging from about 400°F to about 1200°F.
13. The process of Claim 12 wherein the hydrogen is contacted with said zinc exchanged zeolite sorbent at temperatures ranging from about 800°F to about 1000°F.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US222,054 | 1981-01-02 | ||
| US06/222,054 US4358297A (en) | 1980-01-02 | 1981-01-02 | Removal of sulfur from process streams |
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| CA000390819A Expired CA1172178A (en) | 1981-01-02 | 1981-11-24 | Removal of sulfur from process streams |
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|---|---|
| US (1) | US4358297A (en) |
| EP (1) | EP0056197B1 (en) |
| JP (1) | JPS57135029A (en) |
| AU (1) | AU553900B2 (en) |
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| US3085380A (en) * | 1959-10-23 | 1963-04-16 | Engineers & Fabricators Inc | Adsorption process |
| US3078634A (en) * | 1959-11-30 | 1963-02-26 | Union Carbide Corp | Sweetening and drying of natural gas |
| NL258555A (en) * | 1959-11-30 | |||
| US3070639A (en) * | 1959-12-15 | 1962-12-25 | Pure Oil Co | Separation of aromatic hydrocarbons using surface-modified solid adsorbent |
| US3078640A (en) * | 1959-12-18 | 1963-02-26 | Union Carbide Corp | Separation of sulfur compounds from vapor mixtures |
| NL259188A (en) * | 1959-12-31 | |||
| NL126665C (en) * | 1960-03-15 | |||
| US3087291A (en) * | 1960-06-22 | 1963-04-30 | C B Southern Inc | Gas sweetening process and apparatus |
| US3300324A (en) * | 1963-05-20 | 1967-01-24 | Mobil Oil Corp | Hydrogen sulfide detection method and control system |
| BE759979A (en) * | 1965-02-10 | 1971-06-07 | Grillo Werke Ag | PROCESS FOR ELIMINATION OF SULFUR IN RESIDUAL GASES |
| GB1173388A (en) * | 1967-06-30 | 1969-12-10 | Leuna Werk Walter Ulbricht Veb | Process for the Isolation of Hydrocarbon Groups |
| US3620969A (en) * | 1969-10-15 | 1971-11-16 | Union Carbide Corp | Desulfurization by selective adsorption with a crystalline zeolitic molecular sieve |
| US3725299A (en) * | 1970-08-06 | 1973-04-03 | Union Carbide Corp | Regeneration of molecular sieves having sulfur compounds adsorbed thereon |
| US3816975A (en) * | 1972-11-14 | 1974-06-18 | Union Carbide Corp | Purification of hydrocarbon feedstocks |
| US4028069A (en) * | 1976-08-30 | 1977-06-07 | Uop Inc. | Purification and drying of hydrocarbon streams with adsorbents |
-
1981
- 1981-01-02 US US06/222,054 patent/US4358297A/en not_active Expired - Fee Related
- 1981-11-24 CA CA000390819A patent/CA1172178A/en not_active Expired
- 1981-12-28 JP JP56210080A patent/JPS57135029A/en active Granted
- 1981-12-30 AU AU79070/81A patent/AU553900B2/en not_active Ceased
- 1981-12-30 DE DE8181306172T patent/DE3169218D1/en not_active Expired
- 1981-12-30 EP EP81306172A patent/EP0056197B1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI490042B (en) * | 2013-05-30 | 2015-07-01 |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0056197A1 (en) | 1982-07-21 |
| DE3169218D1 (en) | 1985-04-11 |
| AU553900B2 (en) | 1986-07-31 |
| US4358297A (en) | 1982-11-09 |
| JPH0147216B2 (en) | 1989-10-12 |
| EP0056197B1 (en) | 1985-03-06 |
| JPS57135029A (en) | 1982-08-20 |
| AU7907081A (en) | 1982-07-08 |
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